Zhang L, et al. - Considering the epidemiological studies having a clear definition of the risk factors for breast cancer, researchers investigated if the distribution of these factors differs among breast cancer subtypes. In this hospital-based case-only study, researchers analyzed 8067 breast cancer patients basing on the Tianjin Cohort of Breast Cancer Cases, comprising of major breast cancer subtypes such as luminal A, luminal B, human epidermal growth factor receptor 2 (HER2)-enriched and basal-like defined by estrogen receptor, progesterone receptor, HER2, and Ki-67 status. Observations revealed similarity in most breast cancer risk factors and tumor markers for different subtypes of breast cancer, except a few factors for certain subtypes, and the difference is not substantial. Different breast cancer molecular subtypes differed mainly in terms of tumor characteristics such as calcification, stage, tumor size, and mammary gland-related hormone levels, etc. They identified the great significance of the molecular classification of breast cancer in guiding clinical work.